1. Field of the Invention
The invention relates to writing instruments and more particularly to a writing instrument comprising a mechanism including a venting channel and an ink conveying channel for reaching a balance between ink in an ink reservoir and ink in an absorbent material, thereby facilitating writing.
2. Description of Related Art
Conventional writing instruments such as marker pens and highlighters have a porous tip of fibrous material for containing the ink supply (i.e., filler-type writing instrument). However, a number of drawbacks have been found in the filler-type writing instruments as detailed below. Ink flow will gradually decrease with the written characters became blurry as writing time increase. Further, there is at least 30% ink remained in the filler when the writing instrument is useless (i.e., waste).
There have been numerous prior writing instruments. For example, Japan Laid-open Patent Publication No. 2534821 discloses a writing instrument comprising an ink supply mechanism capable of mixing air and ink. However, it is disadvantageous due to complicated components, high precision requirements, and high manufacturing cost.
China Patent Publication Numbers CN1749029A and CN101032905A both disclose a writing instrument comprising a plurality of interconnected ink tubes. However, how to accommodate the ink tubes in a small interior of the writing instrument is always an issue to be solved.
U.S. Publication No. US20030068191A1 discloses a writing instrument comprising a plurality of small ink chambers in the axis direction for conveying ink to a writing element. However, it has complicated components and there is no venting mechanism. Unfortunately, its ink flow may be interrupted when writing is quick.
Notwithstanding the prior art, the invention is neither taught nor rendered obvious thereby.